These investigations studied the fundamentals of how plants perceive gravity and develop in microgravity. It informs how gene regulation is altered by spaceflight conditions.

In this study transcriptome profiling was used to gain insight into the spaceflight adaptation role of Altered response to gravity-1 (Arg1) a gene known to affect gravity responses in plants on Earth. The study compared expression profiles of cultured lines of Arabidopsis thaliana derived from wild type (WT) cultivar Col-0 to profiles from a knock-out line deficient in the gene encoding (ARG1 KO) both on the ground and in space. The cell lines were launched on SpaceX CRS-2 as part of the Cellular Expression Logic (CEL) experiment of the BRIC17 spaceflight mission. The cultured cell lines were grown within 60mm Petri plates in Petri Dish Fixation Units (PDFUs) that were housed within the Biological Research In Canisters (BRIC) hardware. Spaceflight samples were fixed on orbit. Differentially expressed genes were identified between the two environments (spaceflight and comparable ground controls) and the two genotypes (WT and ARG1 KO). Each genotype engaged unique genes during physiological adaptation to the spaceflight environment with little overlap. Most of the genes altered in expression in spaceflight in WT cells were found to be Arg1-dependent suggesting a major role for that gene in the physiological adaptation of undifferentiated cells to spaceflight.

To understand gene expression responses in confluent human fibroblast in microgravity conditions to bleomycin treatment. Confluent human fibroblasts AG01522 were flown to the International Space Station (ISS). After three day on ISS the cells were treated with bleomycin at 1.0 microg/ml for 3 hours. The cells were washed and fixed with RNALater. Total RNA were isolated after the samples were returned to earth and subject to microarray analysis.

Controlled hypobaria presents biology with an environment that is never encountered in terrestrial ecology yet the apparent components of hypobaria are stresses typical of terrestrial ecosystems. High altitude for example presents terrestrial hypobaria always with hypoxia as a component stress since the relative partial pressure of O2 is constant in the atmosphere. Laboratory-controlled hypobaria however allows the dissection of pressure effects away from the effects typically associated with altitude in particular hypoxia as the partial pressure of O2 can be varied. In this study whole transcriptomes of plants grown in ambient (97 kPa/pO2 = 21 kPa) atmospheric conditions were compared to those of plants transferred to five different atmospheres of varying pressure and oxygen composition for 24 h: 50 kPa/pO2 = 10 kPa 25 kPa/pO2 = 5 kPa 50 kPa/pO2 = 21 kPa 25 kPa/pO2 = 21 kPa or 97 kPa/pO2 = 5 kPa. The plants exposed to these environments were 10 day old Arabidopsis seedlings grown vertically on hydrated nutrient plates. In addition 5 day old plants were also exposed for 24 h to the 50 kPa and ambient environments to evaluate age-dependent responses. The gene expression profiles from roots and shoots showed that the hypobaric response contained more complex gene regulation than simple hypoxia and that adding back oxygen to normoxic conditions did not completely alleviate gene expression changes in hypobaric responses.

We investigated differentially regulated genes in human Jurkat T lymphocytic cells in 20s and 5min microgravity and in hypergravity and compared expression profiles to identify potential gravity-regulated genes and adaptation processes.

RAD51 a multifunctional protein plays a central role in DNA replication and homologous recombination repair and is known to be involved in cancer development. We identified a novel role for RAD51 in innate immune response signaling. Defects in RAD51 lead to the accumulation of self-DNA in the cytoplasm triggering a STING-mediated innate immune response after replication stress and DNA damage. Our data suggest that in addition to playing roles in homologous recombination-mediated DNA double-strand break repair and replication fork processing RAD51 is also implicated in the suppression of innate immunity. Thus our study reveals a previously uncharacterized role of RAD51 in initiating immune signaling placing it at the hub of new interconnections between DNA replication DNA repair and immunity. Overall design Gene expression analysis of WT and sh RAD51 HT1080 cells was carried out before and after 1 Gy of high LET Fe particle radiation.

Spaceflight results in a number of adaptations to skeletal muscle including atrophy and shifts towards faster muscle fiber types. To identify changes in gene expression that may underlie these adaptations microarray expression analysis was performed on gastrocnemius from mice flown on the STS-108 shuttle flight (11 days 19 hours) versus mice maintained on earth for the same period. Additionally to identify changes that were due to unloading and reloading microarray analyses were conducted on calf muscle from ground-based mice subjected to hindlimb suspension (12 days) and mice subjected to hindlimb suspension plus a brief period of reloading (3.5 hours) to simulate the time between landing and sacrifice of the spaceflight mice.

Ionizing radiations are categorized by linear energy transfer (LET) into low-LET and high-LET. High-LET is considered to have a higher relative biological effectiveness (RBE) than low-LET radiations. However the details of the effects have not been clearly determined. The aim of this study was to characterize the difference between high-LET and low LET radiations. The global effects of the three types of high-LET radiations (fast neutron heavy ion (C) and thermal neutron) were compared with the low-LET radiation (gamma ray) using yeast DNA microarrays. Highly induced genes by the three types of high-LET radiations were those genes related to oxidative stress. Oxidative stress was one of the common factors associated with the four types of radiations. Oxidative stress induced by high-LET radiations may be more serious than that induced by gamma rays. Additionally genes related to protein synthesis and the ubiquitin and proteasome system were detected. This suggests that more protein damages can be induced by high-LET radiation that denatures the proteins in yeast cells. The genes specifically altered by each type of high-LET radiation were also studied. Overall design: This series contains 4 kinds of irradiation-induced gene expression profiles. Triplicates hybridization was done in each irradiation exposure and each array have high and low power scanned data respectively. All biological samples were collected independently.

Accumulating data suggest that the biological responses to high and low doses of radiation are qualitatively different necessitating the direct study of low dose responses. Most such studies have utilized 2-dimensional culture systems which may not fully represent responses in 3-dimensional tissues. To gain insight into low dose responses in tissue we have profiled global gene expression in EPI-200 a 3-dimensional tissue model from MatTek that imitates the structure and function of human epidermis at 4 16 and 24 hours after exposure to high (2.5 Gy) and low (0.1 Gy) doses of low LET protons. Untreated controls and samples exposed to 10 cGy or to 2.5 Gy were analyzed at three different times (4 16 or 24 hours after exposure). Three biological repeats were performed for each condition

Transcriptional profiling of mammary tissue irradiated at 10 weeks of age with either 100 cGy sparsely ionizing gamma-rays or 10 cGy or 30 cGy densely ionizing radiation (350 MeV/amu Si). Mammary tissue was collected 1 weeks 4 weeks and 12 weeks post-irradiation. Four radiation treatment groups: sham 100 cGy sparsely ionizing gamma-rays 10 cGy or 30 cGy densely ionizing radiation (350 MeV/amu Si). Three time points post-irradiation (1 4 and 12 weeks). Three or four replicates per time point.